Origin of Infrared Point Sources Isolated from Molecular Clouds

这个项目的目的是研究从分子云中分离出来的原恒星候选者的起源。1983年，IRAS卫星首次探测到这些红外点源。它们伴随着波长为25-60微米的冷色光谱，这是在分子云中形成的原恒星的特征。然而，在<13>我们早些时候使用名古屋4米射电望远镜对天鹅座地区（80&lt;l[deg]&lt;100）的分子云进行大规模^ CO（J=1-0）调查的过程中（Dobashi等，1994，Astrophysical Journal Suppl.，我们<13>对这些远离分子云的原恒星候选者特别感兴趣，并试图研究它们的起源。在研究的早期阶段，我们认为这些冷点源可能是那些在早期没有被探测到的原恒星，而在早期，它们的母云可能是一种新的源，因此我们认为它们可能是一种新的源，而在早期，它们可能是一种新的源。我们认为，这些源可能是一种新的源，而在早期，它们可能是一种新的源。我们认为，这些源可能是一种新的源，而在早期，它们可能是一种新的源。我们认为，这些新的源可能是一种新的源，而在早期，它们可能是一种新的源，而在早期，它们可能是一种新的源 ...更多信息 由于<13>某些原因，r ^ CO观测值。人们还期望这些源的一部分应该是星系或行星状星云，它们具有类似于原恒星的红外特性。为了检验所有这些可能性，我们<12>使用具有17“高角分辨率的野边山45米望远镜对从分子云中分离出来的-250颗孤立的原恒星候选者进行了灵敏的^ CO观测。结果，我们检测到了<12>约70%的孤立源的^ CO排放，表明它们可能是与分子云相关的原恒星。这些云中大约有一半是高度致密的分子云，直径只有几个弧分，其余的云显示出非常高的径向速度，表明它们是相当遥远的云，因此它们在早期的^ CO观测中没有被发现<13>。其余的来源（-30%）仍然未知，我们仍在调查其来源。最后，我们已经将这种孤立的原恒星候选者的搜索扩展到银河平面的更大部分（80&lt;l[deg]&lt;180），以检查它们的普遍性。结果表明，这类孤立源在天空中非常丰富，占所有具有类原恒星红外特性的红外源的50-60%。少

The purpose of this project is to investigate the origin of protostellar candidates isolated from molecular clouds. These sources were first detected by IRAS satellite in 1983 as infrared point sources. They are accompanied by the cold color spectrum at the wave lengths 25-60 micron, which is a characteristic feature of protostars forming in molecular clouds. However, on the way of a large-scale ^<13>CO (J=1-0) survey for molecular clouds in the Cygnus region (80<l[deg]<100) that we made earlier using the Nagoya 4m radio telescopes (Dobashi et al.1994, Astrophysical Journal Suppl., vol.94, p.419), we found that as much as >60% of these cold point sources are located outside dense gaseous material traced in ^<13>CO.These protostellar candidates away from molecular clouds were our particular interest, and we attempted to investigate their origin.On an early stage of the research, we expected that these sources might be really protostars whose parent clouds escaped detection in the earlie … More r ^<13>CO observations for some reasons. It was also expected that a part of these sources should be galaxies or planetary nebulae whose have infrared properties are similar to protostars. In order to examine all these possibilities, we achieved sensitive ^<12>CO observations using the Nobeyama 45m telescope having the high angular resolution 17"toward -250 isolated protostar candidates isolated from molecular clouds. As the result, we detected ^<12>CO emission toward -70% of the isolated sources, indicating that they are likely to be protostars associated with the molecular clouds. About a half of these clouds are highly compact molecular clouds with a diameter of a few arcminuites, and the rest show very high radial velocities indicating that they are quite distant clouds, for which they escaped detection in the earlier ^<13>CO observations. The rest of the sources (-30%) remains unknown, and we are still investigating their origin. Finally, we have extended the search for such isolated protostelar candidates over a greater portion of the galactic plane (80<l[deg]<180) in order to check their ubiquitousness. The result implies that such isolated sources are rich in the sky, occupying 50-60% of all the infrared sources with protostar like infrared properties. Less